Your bloodstream is a messy, tumbling universe of many inhabitants — all of them racing around, eternally hurried, never quite finishing the work they intended to do. Luckily, medical science has made something of an art of capturing this chaos, as the common blood test is perhaps the most useful tool we have to assess a person’s health.

We’re getting so good, in fact, that just about every major disease has been found, in some capacity, to show up as certain risk factors in a blood test. These include: concussions, cancers, obesity, heart attack, cataracts, developmental delays in newborns, multiple sclerosis, Alzheimer’s disease, fibromyalgia, diabetes, and even death. Countless lives have been saved as a result of these diagnoses, yet on an individual level an important question persists: How much speculation about your health is too much?

For blood tests to mean anything, scientists need to find telltale “biomarkers.” Basically, biomarkers are the red flags in your blood. They can be substances or states, meaning they can be specific tracers introduced into the body, like in the case of certain radioactive isotopes that rainbow under an X-ray, or they can be electrical signals coming from your brain.

Biomarkers also exist naturally in your body. Such is the case with prostate-specific antigens, or PSA. Over time, science has discovered that the greater presence of PSA has a direct correlation to the size of a man’s prostate, which could indicate the incidence of cancer. Blood tests rely on these naturally-occurring associations: The higher your number is, the greater your chance is for some known disease or condition.

The problem is, biomarkers aren’t perfect. PSA tests, for instance, have a notoriously high false-positive rate. They’re highly sensitive in their testing but equally unspecific. In other words, while they are quite good at detecting cancer, they tend to overestimate what else is going on, which means doctors may order painful follow-up biopsies even though there is no cancer present.

Doctors, for their part, may be falling into something of a statistical trap. One 1982 study asked physicians a hypothetical question. The skeleton of the problem has been changed multiple times over the decades, but the effect is equally perplexing: John says he’s itchy. There’s an allergy test that can determine whether he has allergies, but like other tests, it comes with a false-positive risk. In this case, it’s 10 percent. The question is: If one percent of the population has the allergy and John’s test results say “Yes,” what are the chances he actually has the allergy?

The correct answer, to many people’s surprise, is seven percent. “Unfortunately,” the researchers wrote, “most physicians (approximately 95 out of 100…) misinterpret the statements about the accuracy of the test and estimate [the prevalence rate] to be about 75%.” Their thinking was backward, the researchers point out. They assumed that the chances John had an allergy given a positive test result were equal to the chances of a positive test result in a patient with cancer. The difference is subtle, but hugely important. “The latter probability is the one measured in clinical research programs and is very familiar, but it is the former probability that is needed for clinical decision making.”

Now multiply these simple errors in reasoning across the dozens of blood tests currently available to patients. Blood tests may be reliable indicators of fat levels and cholesterol in the blood, but when it comes to associating the results with larger, more urgent diseases — especially those that come with painful or costly treatment regimens — not all information can be trusted. Now more than ever, patients should stick to the sage advice: Get a second opinion.

NO PURCHASE OR PAYMENT NECESSARY TO ENTER OR WIN. A PURCHASE OR PAYMENT WILL NOT INCREASE YOUR CHANCES OF WINNING. The Giveaway is sponsored by IBT Media Inc., 7 Hanover Square, 5th Floor, New York, NY 10004 (“Sponsor”). The Giveaway is void where prohibited or restricted by all applicable law, and all applicable federal, state and local laws and regulations apply. Winners are responsible for any taxes, customs, and duties and like amounts connected with the prizes.

1. ELIGIBILITY. The Giveaway is open only to legal residents of the 50 states of the United States and the District of Columbia who are the age of majority in their respective jurisdiction at the time of entry (19 in AL and NE and 18 in all other states). Sponsor and its advertising or promotion agencies, those involved in the production, development, implementation or handling of this Giveaway, any agents acting for, or on behalf of Sponsor, its respective affiliates, subsidiaries, licensees, service providers, and any other person or entity associated with this Giveaway are referred to as the “Giveaway Entities.” Employees, officers, and directors of the Giveaway Entities and members of their immediate families (spouses, children, siblings, parents and their spouses), and/or persons living in the same household as such persons, whether or not related, are ineligible to enter this Giveaway.

2. PROMOTION ENTRY PERIOD: The Giveaway begins on July 1, 2015 at 12:00 a.m. EST and ends at 11:59:59 p.m. September 31, 2015 (the “Giveaway Period”). When applicable, the Sponsor’s computers will be deemed the official time keeping devices for the Giveaway promotion.

3. HOW TO ENTER. You will receive one entry into the random drawing for the Giveaway Period when you provide a verified e-mail through our designated modal window interface. Limit one (1) entry per person/email address. Multiple entries will be disqualified. All previous winners of any giveaway or contest sponsored by IBT Media are not eligible to enter. Any effort by an entrant to misrepresent himself or herself through the use of aliases or multiple e-mail addresses will disqualify that entrant. Registrations generated by a script, macro or other automated means are void. You must be the rightful owner of the email address provided. In the event of a dispute as to the identity of the winner, the winner will be deemed to be the authorized account holder of the email address provided at the time of entry. Entrants must provide all information requested to be eligible to win. Incomplete or unintelligible entries, in the sole discretion of Sponsor, will be disqualified. Sponsor will not verify receipt of entries and assumes no responsibility for late, lost, damaged, misidentified or misdirected entries.

4. PRIZE DRAWINGS AND NOTIFICATION OF CHOSEN ENTRANTS. A random drawing will be conducted by Sponsor on or about the first week following the Giveaway Period from among all eligible entries received to award one prize (described below). Selected entrants will be notified by email and will be required to respond (as directed) to the e-mail notification within 72 hours of attempted notification. Failure to respond timely to the notification may result in forfeiture of the prize. Selected entrants may also be required to complete an affidavit of eligibility and liability / publicity release (except where such a requirement is prohibited by law). If the completed Release is not returned within the time specified, the prize may be forfeited.

One (1) Prize per Giveaway Period: An Apple Watch Sport™, which is a registered trademark of Apple Inc. Approximate Retail Value: $349. Limit one (1) prize per person/household. No substitution, transfer, or cash equivalent for any prize, except that Sponsor, at its sole discretion, may substitute a prize with a prize of equal value, due to unavailability of advertised prize. Each prize will be awarded provided each prize is properly claimed. The prize will be shipped by Sponsor to the winners within 1-5 weeks of the receipt of a signed affidavit for approved entries. Prize winners are responsible for all taxes and fees related to any prize received. Actual retail value of prizes may vary due to market conditions. The difference in value of prize as stated herein and value at time of prize notification, if any, will not be awarded.

5. ODDS. The odds of winning a prize will depend on the number of eligible entries received for the Giveaway Period.

6. MARKETING AND PRIVACY. Information collected in connection with entries received for this Giveaway will be used for marketing purposes. By entering the Giveaway, entrants consent to receive marketing emails with updates, offers and promotions from Sponsor or third parties. Entrants may follow instructions contained in each subsequent email communication to opt-out of receiving future email communications, however, Sponsor may still use the email address provided to notify entrant if they have been selected as a winner of this Giveaway.

7. CONDITIONS FOR PARTICIPATION. Giveaway is subject to these Official Rules. By participating, entrants agree to be bound by these complete Official Rules. All decisions of Sponsor are final and binding; and entrants agree to waive any right to claim ambiguity in the Giveaway or these Official Rules, except where prohibited by law. In addition, each entrant represents and warrants that all information contained in his/her registration entry is true and accurate. By accepting a prize, winners agree to release, defend, indemnify and hold harmless the Sponsor, its attorneys, affiliates, together with the respective directors, employees, officers, licensees, licensors and agents of each, including without limitation, their respective advertising and promotion entities and any person or entity associated with the production, judging, or administration of the Giveaway (collectively, the “Releasees”) from any and all loss, damage, injury, death, or other liability, either at law or equity, whether known or unknown, asserted or non-asserted, arising from or in connection with awarding, receipt and/or use or misuse of prize or participation in the Giveaway. This Promotion shall be governed by, and construed in accordance with, the laws of the State of New York, regardless of conflicts of laws principles. Any action or litigation concerning this Promotion shall take place exclusively in the federal or state courts sitting in New York County, New York, and each entrant expressly and irrevocably consents to the jurisdiction of and venue in such courts and waives all defenses of lack of jurisdiction and inconvenient forum with respect to such courts. Each entrant agrees to service of process by mail or other method acceptable under the laws of the State of New York. ANY CLAIMS, JUDGMENTS AND/OR AWARDS SHALL BE LIMITED TO ACTUAL OUT-OF-POCKET COSTS ASSOCIATED WITH ENTERING THIS PROMOTION. REGISTERED CONTESTANT HEREBY WAIVES ANY RIGHTS OR CLAIMS TO ATTORNEY'S FEES, INDIRECT, SPECIAL, PUNITIVE, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ENTRANT, WHETHER FORESEEABLE OR NOT AND WHETHER BASED ON NEGLIGENCE OR OTHERWISE. EACH PARTY EXPRESSLY WAIVES ANY RIGHT TO A JURY. The releases hereunder are intended to apply to all claims not known or suspected to exist with the intent of waiving the effect of laws requiring the intent to release future unknown claims. This Giveaway is void outside the U.S. and where prohibited or restricted by law, and subject to applicable federal, state, and local laws. Sponsor reserves the right to disqualify any entrant it finds to be tampering with the entry process or the operation of the Giveaway or violating these Official Rules.

8. PUBLICITY AND RELEASE FORMS: Sponsor reserves the right to use the Giveaway for publicity purposes in any media, and to use the name, likeness, and hometown name and/or prize information of prize winners as part of that publicity, without any compensation or prior review, unless prohibited by law. Each prize winner will be required to submit a declaration and a liability/publicity release and confirmation that the prize winner has followed the rules of the Giveaway, in the form supplied by Sponsor (the "Declaration and Release"), and signed by the prize winner. The Declaration and Release must be signed and returned within seven (7) days of notification. Prize won by an eligible entrant who is a minor in his/her state of residence will be awarded to minor's parent or legal guardian who must sign and return all required documents. In the event the Affidavit and Release is not returned within this period, an alternate winner may be selected for such prize. Any prize notification or prize returned to Sponsor as undeliverable will result in the awarding of that prize to an alternate winner (who will be required to comply with similar procedures).

9. LIMITATION OF LIABILITIES: The Releasees shall not be liable for: (i) late, lost, delayed, stolen, misdirected, incomplete unreadable, inaccurate, garbled or unintelligible entries, communications or affidavits, regardless of the method of transmission; (ii) telephone system, telephone or computer hardware, software or other technical or computer malfunctions, lost connections, disconnections, delays or transmission errors; (iii) data corruption, theft, destruction, unauthorized access to or alteration of entry or other materials; (iv) any injuries, losses or damages of any kind caused by the prize or resulting from acceptance, possession or use of a prize, or from participation in the Giveaway; or (v) any printing, typographical, administrative or technological errors in any materials associated with the Giveaway. In the event that more prize notice emails are sent for any of the prizes than the number of prizes available as specified in these Official Rules, a random drawing will be conducted from all entrants who received such notices to award number of prizes specified in these Official Rules. Sponsor disclaims any liability for damage to any computer system resulting from participating in, or accessing or downloading information in connection with this Giveaway, and reserve the right, in their sole discretion, to cancel, modify or suspend the Giveaway should a virus, bug, fraud, computer problem, unauthorized intervention or other causes beyond Sponsor’s control, corrupt the administration, security or proper play of the Giveaway. Sponsor may prohibit an entrant from participating in the Giveaway or winning a prize if, in its sole discretion, it determines such entrant is attempting to undermine the legitimate operation of the Giveaway in any way by cheating, hacking, deception, or any other unfair playing practices of intending to annoy, abuse, threaten or harass any other players or Sponsor representatives. Use of any automated system to participate is strictly prohibited and will result in disqualification. Sponsor may disqualify at its sole discretion any entries it believes are created by an automated system or exceed the maximum of one entry per natural person/email address. Disputes regarding these Official Rules and/or this Giveaway will be governed by the internal laws of the State of New York, without regard to conflicts of laws principles. Any and all legal actions or claims arising in connection with this Giveaway must be brought in a court of competent jurisdiction within New York County, New York or, at Sponsor’s sole discretion, anywhere else in the United States. CAUTION: ANY ATTEMPT TO DELIBERATELY DAMAGE THE IBT MODAL WINDOW OR UNDERMINE THE LEGITIMATE OPERATION OF THE GIVEAWAY MAY BE IN VIOLATION OF CRIMINAL AND CIVIL LAWS AND WILL RESULT IN DISQUALIFICATION FROM PARTICIPATION IN THE GIVEAWAY. SHOULD SUCH AN ATTEMPT BE MADE, SPONSORS RESERVE THE RIGHT TO SEEK REMEDIES AND DAMAGES (INCLUDING ATTORNEY FEES) TO THE FULLEST EXTENT OF THE LAW, INCLUDING CRIMINAL PROSECUTION.

10. PRIVACY. Please refer to Sponsor’s privacy policy located at http://www.medicaldaily.com/privacy-policy for important information regarding the collection, use and disclosure of personal information by Sponsor.

11. WINNER LIST. For names of the winners, send your request in a self-addressed, stamped envelope to: The IBT Media Email Address Monthly Giveaway Winners List, 7 Hanover Square, 5th Floor, New York, NY 10004. Winner lists will be sent out once winners have been verified. The name of the all winners will be posted only for 30 days after the end of the Entry Period.

BY ENTERING, YOU AGREE THAT YOU HAVE READ AND ACCEPTED ALL OF THESE GIVEAWAY RULES.